In the field of semiconductor processing, there have been several attempts to use lasers to convert thin amorphous silicon films into polycrystalline films. For example, in James Im et al., “Crystalline Si Films for Integrated Active-Matrix Liquid-Crystal Displays,” 11 MRS Bulletin 39 (1996 ) an overview of conventional excimer laser annealing technology is described. In such conventional system, an excimer laser beam is shaped into a beam having an elongated cross-section which is typically up to 30 cm long and 500 micrometers or greater in width. The shaped beam is stepped over a sample of amorphous silicon (i.e., by translating the sample) to facilitate melting thereof and to effectuate the formation of grain-shape and grain boundary-controlled polycrystalline silicon upon the re-solidification of the sample. Such techniques has been referred to a sequential lateral solidification (“SLS”) of the melted portions of the sample to effectuate the growth of longer grain boundaries therein so as to achieve, e.g., uniformity among other thing.
Various techniques processes, masks and samples have been previously described which utilize various SLS techniques, to effectively process the sample. For example, International Publication No. 02/086954 describes a method and system for providing a single-scan, continuous motion sequential lateral solidification of melted sections of the sample being irradiated by beam pulses. In this publication, an accelerated sequential lateral solidification of the polycrystalline thin film semiconductors provided on a simple and continuous motion translation of the semiconductor film are achieved, without the necessity of “microtranslating” the thin film, and re-irradiating the previously irradiated region in the direction which is the same as the direction of the initial irradiation of the thin film while the sample is being continuously translated.
One of the objects of the present invention is to increase the grain size of the melted and re-solidified SLS processed samples and/or portions thereof via limited irradiation of such portions and/or sample for obtaining a desired grain length.